Language Reference

How Type Is Determined

Each user-defined function or named entity has a data type. (The type of an entity accessed by host or use association is determined in the host scoping unit or accessed module, respectively.) The type of a name is determined, in the following sequence, in one of three ways:

1. Explicitly, in one of the following ways:
   • From a specified type declaration statement (see Type Declaration for details).
   • For function results, from a specified type statement or its FUNCTION statement.
2. Implicitly, from a specified IMPLICIT type statement (see IMPLICIT for details).
3. Implicitly, by predefined convention. By default (that is, in the absence of an IMPLICIT type statement), if the first letter of the name is I, J, K, L, M, or N, the type is default integer. Otherwise, the type is default real.

In a given scoping unit, if a letter, dollar sign, or underscore has not been specified in an IMPLICIT statement, the implicit type used is the same as the implicit type used by the host scoping unit. A program unit and interface body are treated as if they had a host with an IMPLICIT statement listing the predefined conventions.

The data type of a literal constant is determined by its form.